Handling of building panels such as drywall or “Sheetrock” panels has presented difficulties, especially for large panels being installed in commercial buildings at heights above a first floor level. drywall panels for such applications may be as large as four feet by twelve feet and weigh one hundred pounds or more. It is readily apparent that any improvement in equipment and procedures for lifting such panels to a required elevated location would be welcomed by installers.
Use of scissors-type lift machines has become a common practice at commercial building sites. These devices have sets of paired extendable arms mounted on a wheeled and powered chassis and a work platform supported by the arms. For safety reasons the platforms have horizontal rails around their outer edges supported by upright posts. The rail structure generally includes an upper rail some three feet above the platform floor and a lower rail halfway between the floor and the upper rail. The rails generally take the form of square or round metal tubing. Lift platforms of this type may be eight feet by three feet or larger in size and provide space for two to three workmen. Such machines are exemplified by U.S. Pat. No. 6,158,550, issued Dec. 12, 2000 to Arnoldy, which patent is hereby expressly incorporated by reference.
Attempts have been made to use existing lift machines for lifting large panels along with the workmen to an elevated working level, with the panel being supported by measures such as placing the panel on edge on a workman's foot extending outside of the platform at each end. This approach is dangerous and difficult to maintain for the period of time required to move the machine from a stack of panels to a desired final location. Other approaches such as placing the panel on top of the platform rail are not effective for large panels owing to a lack of space, and may result in damaging the panel when it comes into contact with metal surfaces or corners.
Desirable features for a panel-supporting device include a bottom channel adapted to allow a panel to be slid on edge into transporting position under conditions avoiding exposure of the panel to scraping or tearing, a means to restrain the panel from sliding out during transport and a means to facilitate movement of the panel when lifted by workmen off the device and into position for installation.